A proposed configuration of a cooling apparatus for internal combustion engine diagnoses failure of a thermostat, based on the sensor value from a temperature sensor mounted at an outlet of a cooling water flow path of an internal combustion engine and the sensor value from a temperature sensor mounted on the upstream side of a radiator in a circulation flow path that is arranged to circulate cooling water from the cooling water flow path of the internal combustion engine through the radiator (for example, Patent Literature 1). This apparatus provides accurate diagnosis of failure of the thermostat when the internal combustion engine is driven by combustive operation or when an electric pump configured to circulate the cooling water is in a stopped state even during intermittent stop of the internal combustion engine or during fuel cutting. This apparatus does not provide accurate diagnosis of failure of the thermostat when the electric pump is driven during intermittent stop of the internal combustion engine or during fuel cutting.